Intel IP Gateway (Global Call) for Linux and Windows 用户手册

2.  In PSTN_OFFERED the application waits for GCEV_CONNECTED from

the IP side.

When the application receives GCEV_CONNECTED it calls:

•  gc_Extension( ) to get the call information from the IP side
•  gc_Listen( ) to tell the IP line device to listen to the PSTN time slot
•  pstnListen( ) which calls ag_Listen( ) or dt_Listen( ) (ag for analog; dt for

digital) to tell the PSTN line device to listen to the IP time slot

•  gc_AnswerCall( ) to answer the call on the PSTN

The state transitions to IP_CONNECTED.

3.  In IP_CONNECTED, when the application receives GCEV_ANSWERED

from the PSTN the state transitions to GATE_CONNECTED.

1.  When either side (PSTN or IP) sends a GCEV_DISCONNECTED event in

any state except for IP_OFFERED, the application calls gc_Unlisten( ) for
the IP side and ag_Unlisten( ) or dt_Unlisten( ) for the PSTN side. The
application also calls gc_DropCall( ) for both sides of the call to disconnect
the call.

The state transitions to GATE_DROP.

2.  When the application receives GCEV_DROPCALL from both sides the

application calls gc_Extension( ) to get RTCP information for the call.

When the application receives GCEV_EXTENSION with the RTCP
information it calls gc_ReleaseCall( ) to release the call.

The state then transitions to GATE_RELEASE.

3.  When the application receives a GCEV_RELEASECALL event it sends

IPTResetSession() and the call state transitions to GATE_NULL.

If a GCEV_DISCONNECTED event is received from the IP side when the state is
IP_OFFERED:

1.  The application calls gc_DropCall( ) for the IP side and the state transitions

to IP_DROP.